1. Field of the Invention
The present invention relates to a display system for displaying an image, and more particularly to a display system for displaying a stereoscopic image for industrial, medical, or domestic use.
2. Description of the Related Art
In a conventional stereoscopic display system, an observer wears glasses for separating right and left images from each other whereby right and left eyes of the observer can selectively see right and left target images, respectively, which are displayed on an image screen in a time-division fashion. In another conventional technique, a lenticular plate is attached to an image screen so that the lenticular plate can separate right and left images from each other and thus right and left eyes of the observer can selectively see right and left target images, respectively.
FIG. 1 illustrates an example of the configuration of the above-described conventional stereoscopic-image display system, which includes glasses 60 capable of separating right and left images from each other, liquid crystal shutters 61a and 61b, a synchronous circuit 62, and color CRT 63 serving as an image display device.
The above first example of a stereoscopic-image display system having such a configuration operates as follows. The color CRT 63 displays stereoscopic images wherein images for right and left eyes are displayed alternately in a time-division fashion. Under the control of the synchronous circuit 62, the liquid crystal shutter 61a of the glasses 60 is opened and thus become transparent only when stereoscopic images for the right eye are displayed, and the liquid crystal shutter 61b is opened and become transparent only when stereoscopic images for the left eye are displayed. As a result, an observer wearing the glasses 60 can observe stereoscopic images for the right eye with his or her right eye, and stereoscopic images for the left eye with the left eye. In this way, stereoscopic vision is provided.
FIG. 2 illustrates the configuration of the second example of a conventional stereoscopic-image display system, which includes a lenticular plate 71 having a large number of stripe-shaped cylindrical lenses and a color CRT 72 serving as an image display device.
This second example of stereoscopic-image display system having such a configuration operates as follows. The color CRT 72 displays simultaneously both stereoscopic images for right and left eyes such that images for right and left eyes are displayed alternately on each half-width stripe of the lenticular plate 71. The right eye of an observer sees only the stereoscopic images for the right eye displayed on the above-described slit-shaped zones through corresponding cylindrical lenses of the lenticular plate 71, and the left eye sees only the stereoscopic images for the left eye displayed on the slit-shaped zones, whereby stereoscopic vision is obtained.
In the first example of the conventional stereoscopic-image display system, however, an observer has to wear troublesome and uncomfortable glasses which separately provide stereoscopic images to right and left eyes of the observer. Another problem in observing stereoscopic images using this technique is flicker due to the switching between the stereoscopic images for right and left eyes.
In the second example of the conventional stereoscopic-image display system, since a stereoscopic image is observed via stripe-shaped lenses, stereoscopic vision can be obtained only when an observer is in a limited narrow area. If the observer moves, degradation occurs in the image. Besides, only a few observers at various positions can observe an image at the same time. Furthermore, image processing is required to provide a stripe-shaped image, which needs an expensive apparatus.
In medical applications, when an endoscopic operation is used, an operator observes a plane image of the inside of a patient's abdominal cavity displayed on a monitor via an endoscope. However, the monitored image of the inside of the abdominal cavity has no characteristic features because the entire abdominal cavity has a single color, and thus it is difficult to give perspective vision. This causes a long operation time, and gives heavy loads to both surgeon and patient. On the other hand, when a conventional stereoscopic-image display system of the above-described first or second type is used in the operation, there are serious problems in practical use such as uncomfortable glasses for separating right and left images, flicker of an image, and limitation in movement of an observer.